Motor-control system



Patented Sept. 30, 1924.

' UNITED STATES PATENT OFFICE.

HOUSE nnncrnro a value.

MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- MOTQR-CONTROL SYSTEM.

Application filed October-'11, 1922. Serial No. 598,664

Toall whom it may concern:

Be it known that I, EDGAR M. BOUTON, a

citizen of the United States, and a resident of East Pittsburgh, in the county of Allegheny andState of Pennsylvania, have invented 'a new and useful Im rovement in Motor-Control Systems, of 'w ich the following is a specification.

My inventlon relates to motor-control systems, and it has particular relation to such systems of control as are employed in connection with elevators, hoists and similar machines.

One object of m invention is to control the starting and the stopping of a directcurrent motor without employing the usual resistors'in the armature circuit.

Another object of my invention is to provide automatic means for obtaining smooth and rapid acceleration and decelerationunderall load conditions.

' A further object of my invention is to obtain a fine degree of speed control and to obtain good regulation at low speeds.

Other objects of my inventlon will appear in the following detailed description.

Various systems of control have been previously devised to operate with eater efficiency than is possible with resistors connected in the armature circuit of a directcurrent motor. Such systems provide some means for impressing a variable voltage upon the motor.

According to my invention, I ropose to employ a motor-generator set of' ess capacity than is required in other systems of variable-voltage control and, in addition, I provide certain automatic features for im- 1 provement of the speed control of a hoist- 'm motor.

y invention will be described in connection with the accompanying drawings, in which i 1 Figure 1 is a diagrammatic representation of circuits and apparatus embodying my invention.

Figs, 2', 3, 4 and 5 represent schematically certain main connections employed in the operation of the system shown in Fig. 1.

Referring particularly to .Fig. 1, a shunt .xwound direct-current motor 1, having an armature 2 and'afield-magnet winding 3 is arranged for connection to a source oi energy comp nsmg conductors 4 and 5.

livers the major Switches 6,7, 8 and 9 are employed for re-,

versing the armature connections of the motor 1. A motor-generator set, comprising a pair of mechanically-connected armatures .11 and 12 and series field-ma et windings 13 and 14, may be connecte in circuit with the motor 1 by means of switches 15 and 16.

Shunt field-magnet windings 17 and 18 co-operate with the series wind 1 ings 13 and 14:, respectively. Shunt field rheostats 19 and'20 are mechanicall connected to be 0 erable simultaneous y. .A manually o era le switch 22 is employed for controlling the electromagnetic switch 16.

Assuming the ap aratus and switches in their illustrated an in-operative positions, either pair of reversing switches 6 and 8 or 7 and 9 may be operatedby means of a. master switch (not shown). Assuming also that line conductors 4. and 5 are receiving energy from the source of pow r, the motorgenerator set will operate and ts armatures 11 and 12 will supply a volta e op osed to that of the line voltage and 0 near y equal value.

The power consumed by the'motor-generator set is merely enough to sup ly the losses of the set when running 1 e. As illustrated, the field-ma nt winding 18 is fully energized, and t e winding 17 is sup lied with a minimum energization. It wil be apparent that the armature 12 de-,

ortion of the countervoltage and, there ore, upon the closure of either pair of reversing switches, as 6 and 8, a mmimum operating voltage, supplied bythe armature 11,- is 1m ressed u on the "motor armature 2; In ad ition to t e current' drawn from the armature 11, a portion of the current absorbed by the armature 2 is supplied from line conductors 4 and 5 throu the armature 12 and the switch 16,, w ich occupies its lower 'posiminimum-voltage excitation; for the arms;-

ture 11 of the'motor-ienerator set,' wh i le the series winding 13 as a-larger' corresponding efiect upon the armature 11, since it carrgesthe entire current generated by the armature 11. This current is just sufficient to operate the armature 2 at. its minimum speed, in accordance with the load conditions imposed upon the motor 1.

The current drawn from line conductors 4 and 5 by the armature 12 is suflicient to operate the armature 11 at substantially uniform speed, which is maintained on account of the maximum excitation of the shunt field-magentwinding 18.

When it is desirable to accelerate the motor 1, switch 22 is closed and rheostats 19 and 20 are manipulated in a clockwise direction, thereby strengthening the field-magnet windin 17 and decreasing the. strength of the fiel-magnet winding 18. vWith increased field strength, the armature 11 develops a corresponding increase in voltage, while the decrease in the strength of the winding 18 effects a decrease in the voltage delivered by the armature 12. There is a corresponding increase in current through the armature 12 from line conductors 4 and 5. This increase is, of course, proportional to the decrease in the counter-voltage delivered by the armature 12. The increase in current traversing the winding 14 tends to strengthen the field and oli'set the effect of too suddenly reducing the energization of winding 18. When the field rheostats 19 and 20 are .in the en'ttreme right-hand positions, the motor 1 is "smoothly and rapidly accelerated in accordance with the gradually decreasing voltage of the armature 12 and a corresponding increase in voltage of the armature 11.

At apredetermined value otvoltage of the armature 2, switch 15 is closed, since its operating coil 23 is responsive to the voltage of the armature 2. The closure of switch 15 shunts the series field-magnet winding 14,

with

and a'portion of the current traversing the armature 12 now flows through the resistor 24 in shunt to the winding 14. v

Switch 16 is provided with a hold-down coil 25, which is responsive to the voltage of the armature 12 and is arranged to release at a suitably low value ofvoltage when over come by the opposing efi'ect of the operating coil 26, which is responsive to the voltage applled to the motor armature 2. Switch 16, in closing, connects the motor 1 directly to lme conductors 4 and 5 and also connects the armature 11 of the motor-generator setv directly'to the line. The armature 11 is now motoring. and draws only sufiicient cur rent to overcome the losses of the motorgenerator set which is now running idly with the armature 12 disconnected. Fig. 2 represents the circuits for producmg; the minimum operating speed of the motor 1, and Fig. 3 represents the connectlonsfor an intermediate higher speed, with rheostats 19 and '20 in the extreme rightand position and with switches 15 and 16 variable source of ener :taneously connecting t e motor to both reoaeae transition period in which switch 15 is closed and series field-magnet winding 14 is shunted by resistor 24. In Fig. 5, the connections correspond to the maximum running speed of the motor 1, in which the motor is connected directly to the line.

To effect deceleration of the motor 1, switch 22 is opened and rheostats 19 and 20 are returned to their initial positions. Switches 15 and 16 return to the lower positions to re-connect the armature 12 in circuit with armatures 2 and 11. Armature 12 generates a voltage that is opposed to the line voltage and will correspondinglyreduce the voltage across the armature2 of the motor 1. The motor 1 will now regenerate, returning current to the line until the counter-electromotive force generated by the ar-. mature 2 has been reduced to the voltage impressed at its terminals. With the con nections as illustrated in Fig. 2, the-armature 12 absorbs its maximum voltage, and sufficient voltage is applied to the armature 2, as previously described for the starting conditions, to operate the motor 1 at its minimum speed.

It should be noted that series field-magnet winding is chosen of suitable value, as. previously indicated, to offset the effect of a too sudden change in the field strength, caused by rapid manipulation ofrheostat 2O correspondingly reduced in size.

, I am aware of the use of boosters in connectlon with the operation of series railway motors, particularly as applied in regenera- I f tive systems. I believe that my system 'embodies novel features of control of particular value in connection with direct-current 1 shunt-wound motors. for hoistingqapplications. These features will be readily reco nized by those skilled inthe art, and modifications may be made without departingfrom the spirit and scope of my invention.

claim as my invention:

1. The combination with a motor ands. source of energy therefor, of an auxiliar sources, means for varying the voltage impres's'ed'oii'said motor and means dependent upon the speed of said motor for rendering one of said sources ineffective.

- 2. The combination with an electric motor having an armature and a source of power means for simu y therefor, of an auxiliary motor-generator set having its armatures connected electrically, means for connecting the armature of said motor in circuit with said motorgenerator set, and means controlled in accordance with the speed of said motor forconnecting said motor directly to the source of power.

3. The combination with an electric motor having an armatur: and a source of power therefor, of an auxiliary motor-generator set having its armatures connected electricall .means for connecting the armature of said motor in circuit with said motor-generator controlling the shunt field-magnet windings oppositely and means comprising the series field-magnet windings for modifying the ef fect of said shunt field-magnet windings.

5. The combination with a motor and a source of energy therefor, of a motor-generator set comprising a pair of direct-current machines having compound field-magnet windings, means for connecting said motor in circuit with said machines, means for controlling the shunt field-magnet windings oppositely, means comprising the series fieldmagnet windings for modifying the effect of said shunt field-magnet windings and means for shunting one of said series fieldmagnet windings.

6. The combination with a motor and a source of energy therefor, a motor-generator set comprising a pair of direct-current machines having compound field-magnet windings, means for connecting said motor in circult with said machines, means for controllin the shunt field-magnet windings o posite y, means comprisin the series eld v fyingtheefl'ect of said shunt field-magnet windin and means controlled in accordance wi the motor power, means for connecting speed for shunting one of said series field-- magnet windings.

7. The combination with an electric motor havin an armature and a source of power there or, of an auxiliary motor-generator set having armatures connected in series relation with each other and to the source of the armature of said motor in series relatlon with one of said auxiliary armatures and means controlled in accordance with the speed of said motor for connecting said motor directly to said source of power.

8. The combination with an electric motor having an armature and a source of power therefor, of an auxiliary motor-generator set having armatures connected in series relation'with each other and to the source of power, means for connecting the armature of said motorin-series relation with one of said auxiliary armatures and means controlled in accordance with the counter-electromotive force of said motor for connecting said motor directly to said source of power.

9. The combination with an electric motor having an armature and a source of power therefor, of an auxlliary motor-generator set having armatures connected in series relation with each other and to the source of.

power, means for connecting the armature .of said motor in series relation with one of said auxilia armatures and means 'controlled in accor ance with the speed of said motor for disconnecting said motor from said motor-generator set. v

10. The combination with an electric motor and a source of power therefor, of an auxiliary motor-generator set having its armatures connected in series relation, means for connecting said armatures to the source of power, means for connecting the motor in circuit with said armatures, means for V8. ing the voltage of said armatures opposite y to control sald motor and means dependent upon the relation of 'said voltages for accelcrating said motor;

In testimony whereof, I have hereunto subscribed my name this 7th day of October 1922.

EDGAR M. BOUTON. v 

